Comparison of feldspathic veneer surface treatments on ceramic bracket SBS, ARI and surface roughness after different debonding/polishing methods: An in vitro study

Abstract

To analyse, in vitro, surface properties and the shear bond strength after debonding and polishing procedures of ceramic brackets directly bonded to 0.3-0.5-mm thick feldspathic veneers. Fifty six feldspathic ceramic veneers samples (0.3 to 0.5-mm thick) were allocated into groups according to veneers surface treatment procedures: (S) glaze layer was retained; (SHF) hydrofluoric (HF) acid etch; (SOXA) Al2O3 sandblasting; and (SB) diamond burs roughening. Specimens were treated with silane Monobond N® and ceramic brackets bonded with Transbond XT®. Shear bonding strength (SBS) was assessed with a universal testing machine and ARI evaluated under a stereomicroscopic coupled to a digital camera. Remaining bonding composite was removed using a porcelain polishing kit and surface roughness assessed with a stylus profilometer. No statistically significant differences were identified for SBS among the study groups (S, SHF, SOXA and SB) (P>0.05). The majority of the specimens presented ARI scores 3 and 2 (P>0.05). All of the study groups presented increased surface roughness after debonding and polishing procedures (P<0.05), with significant greater values observed in SB group (RaF: 1.27±0.41; RzF: 6.23±1.82), (P<0.05). Surface treatment with hydrofluoric acid etch, Al2O3 sandblasting and diamond bur did not enhance SBS of orthodontic brackets bonded to ceramic veneers. Ceramic surfaces treated with diamond burs presented significantly increased roughness after adhesive removal.